The youngest daughter Sybil has begun to grow close to the chauffeur Branson due to their mutual interest in politics. To everyone's surprise, Cora is discovered to be pregnant, which casts the issue of who will inherit Downton Abbey into doubt – but her maid O'Brien, who mistakenly thinks Cora plans to replace her, causes her to fall and miscarry the baby. As a result of Edith telling the Turkish ambassador her secret, Mary takes revenge by ruining her sister's chances with a potential suitor. Matthew proposes to Mary, who has begun to return his feelings, but after she appears uncertain, Matthew says he can't be sure whether she would be marrying him for himself or the estate. He announces he is leaving Downton Abbey. At the end of a party, Mary's father Robert receives a message and announces that Britain has entered into war with Germany.
